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Re: NumberForm question

  • To: mathgroup at smc.vnet.net
  • Subject: [mg82006] Re: [mg81985] NumberForm question
  • From: DrMajorBob <drmajorbob at bigfoot.com>
  • Date: Tue, 9 Oct 2007 05:38:24 -0400 (EDT)
  • References: <20828645.1191825480672.JavaMail.root@m35>
  • Reply-to: drmajorbob at bigfoot.com

I thought I had an answer: the 2 in your InputForm output is in the 17th 
decimal position (counting from the leading decimal as 1st position), so 
16-digit precision leaves it out in the NumberForm output.

$MachineEpsilon

2.22045*10^-16

BUT:

NumberForm[x,{100,100}]

1.0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000

 From that, I'd think x is simply 1.0 (contradicting the InputForm).

But no, since:

RealDigits[x, 2]

{{1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
   0, 0, 0, 0, 0, 0, 0, 1}, 1}

So... you got me, I have no idea why!

Bobby

On Mon, 08 Oct 2007 01:03:48 -0500, Yaroslav Bulatov  
<yaroslavvb at gmail.com> wrote:

> x=1+$MachineEpsilon;
> InputForm[x]
> NumberForm[x,{16,16}]
>
> Why does the result printed by NumberForm seem smaller?
>
>
>



-- 

DrMajorBob at bigfoot.com


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